A storage battery is a widely used power supply. Multiple unit batteries are generally combined in series or parallel according to voltage and capacity required by load, the voltage being increased through series connection, the capacity being increased through parallel connection. The current method is that, first all the positive electrodes of a certain amount of the unit batteries are connected together through a bus, and then all the negative electrodes together through another bus, thus obtaining a parallel branch. The multiple unit batteries, corresponding to the same position in the parallel branch, are connected according to sequence of the positive electrode and the negative electrode, and thus multiple series branches are obtained. A combination of series connection and parallel connection of the multiple unit batteries can thus be obtained. Therefore, the connection of the bus with the positive electrode and the negative electrode of the battery by welding as well as battery fixing is necessary step for assembling storage batteries or battery sets, with the operation more troublesome and the security not high, either.